This invention relates to a novel oil filter apparatus. More particularly the invention comprises an electronic apparatus for monitoring and signaling the condition of an oil filter operable to remove contaminates from engine lubricating oils.
Internal combustion engines, and the like, having a large number of relative moving parts, are continuously lubricated by an associated lubrication system. The lubrication system typically includes an oil sump from which oil is pumped in a fluidic loop or splashed around and over moving engine parts such as valves, piston rods, etc. In order to eliminate abrasives which become suspended within the lubrication system the oil is continuously pumped through an oil filter mounted in series within the oil loop. If contaminates can be reliably removed it becomes unnecessary to change the oil since the oil per se does not "wear out" but rather becomes contaminated with impurities.
It is critical to maintain lubricating oils clean when lubricating expensive machinery such as internal combustion machines. The prior art teaches many variations in replaceable filters for such purposes. It is difficult for the operator of machinery, however, to determine when a filter must be replaced. Therefore, manufacturers of such equipment typically recommend that filters should be replaced after "so many hours of operation" or "after so many miles traveled." These methods are imprecise and often lead to the retention of filters past their useful life with subsequent damage to an engine or the filters are replaced unnecessarily before replacement is required. As more expensive and sophisticated filtering equipment is utilized, and the price of lubricating oil increases, an incentive exists to extend the useful life of the filter while concomitantly accurately determining when a filter needs replacement.
Other workers in the field have developed systems for sensing the degree of resistance filtered oil encounters via its travel through a filter by sensing the difference in oil pressure between an inlet and outlet and, upon sensing a predetermined difference, activating an alarm for signaling the operator that the filter is clogged.
At least one previously known system is designed to signal actuation of an engine mounted bypass valve. In this regard the valve structure is placed in series with an engine battery and in parallel with an alarm. In the event the bypass valve and circuit are opened the battery will conduct through the alarm thus signaling opening of the bypass valve.
While such a system provides at least a degree of theoretical appeal one disadvantage is that alarm systems of this type require special fitting within an engine block and oil system. Additionally a potential for sparking exists within the oil system when the bypass electrical circuit is broken. Still further such bypass valves are subject to "chatter" during starting, etc. due to temporary high pressures within the system.
One system which advantageously obviates many of the disadvantages of previously known bypass systems is disclosed and claimed in my U.S. Pat. No. 4,246,109 issued Jan. 20, 1981. The disclosure of this patent is hereby incorporated by reference as though set forth at length.
A difficulty with my prior disclosed bypass system is that the bypass structure tends to be relatively expensive when compared with conventional filter elements. Moreover the inferior character of most filtering media and systems dictates frequent replacement.
The difficulties suggested in the preceding are not intended to be exhaustive, but rather are among many which may tend to reduce the effectiveness of prior oil filter methods and apparatus. Other noteworthy problems may also exist; however, those presented above should be sufficient to demonstrate that oil filter apparatus appearing in the past will admit to worthwhile improvement.